Cartridge for an aerosol-generating system

ABSTRACT

A cartridge for use in an aerosol-generating system is provided, including a liquid storage portion including a housing configured to hold a liquid aerosol-forming substrate, the liquid storage portion including at least two parts in fluid communication with each other; a first part of the liquid storage portion including a heater assembly, a first capillary material, provided in contact with the heater assembly, and a second capillary material in contact with the first capillary material and spaced apart from the heater assembly by the first capillary material; and a second part of the liquid storage portion including a container configured to hold the liquid aerosol-forming substrate in liquid form to supply the liquid to the second capillary material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of and claims the benefitof priority under 35 U.S.C. § 120 to U.S. application Ser. No.15/117,663, filed on Aug. 9, 2016, which is a U.S. National Stageapplication of PCT/EP2014/077852, filed on Dec. 15, 2014, and claimsbenefit of priority under 35 U.S.C. § 119 from European PatentApplication Nos. 14154552.5, filed on Feb. 10, 2014; 14154553.3, filedon Feb. 10, 2014; and 14154554.1, filed on Feb. 10, 2014. The entirecontents of each of which are incorporated herein by reference.

The present invention relates aerosol-generating systems. In particular,the invention relates to handheld aerosol-generating system, such aselectrically operated smoking systems. Aspects of the invention relateto a cartridge for aerosol-generating systems, in particularelectrically operated smoking systems.

One type of aerosol-generating system is an electrically operatedsmoking system. Handheld electrically operated smoking systemsconsisting of a device portion comprising a battery and controlelectronics, and a cartridge portion comprising a supply ofaerosol-forming substrate, and an electrically operated vapouriser, areknown. A cartridge comprising both a supply of aerosol-forming substrateand a vapouriser is sometimes referred to as a “cartomiser”. Thevapouriser typically comprises a coil of heater wire wound around anelongate wick soaked in liquid aerosol-forming substrate. Capillarymaterial soaked in the aerosol-forming substrate supplies the liquid tothe wisk. The cartridge portion typically comprises not only the supplyof aerosol-forming substrate and an electrically operated vapouriser,but also a mouthpiece, which the user sucks on in use to draw aerosolinto their mouth.

In some types of electrically operated aerosol-generating devices, areservoir of aerosol-forming liquid is provided in a tank. In use in theaerosol-generating system, the liquid is conveyed from the tank bycapillary action into the wick of a coil wick heater assembly where theliquid is vaporized. When a user draws at the mouthpiece an airstreamflows over the heater assembly and the generated aerosol is inhaled bythe user.

A problem of such a tank device is, that the system stops generating theaerosol if the device is held at such an angle that the liquidaerosol-generating substrate in the tank is not in contact with thecapillary system. Moreover, these systems can be prone to leakage forexample where the liquid from the tank floods the core or leaks throughthe airflow path.

In other systems, the liquid storage portion of a cartridge is filledwith a capillary medium. The liquid aerosol-generating substrate is heldin the capillary material and delivered to the wick. With such systemthe above mentioned problems of the holding angle and the risk ofleakage can be reduced. However, some residual liquid will remain in thecapillary material after usage, leading to wastage. Further, there canbe an inconsistency in puff deliveries in such systems due to decreasingsaturation of the capillary medium during usage, which does not allowfor a constant high quality smoking experience.

It would be desirable to have a cartridge that avoids one or more of theabove mentioned or other disadvantages, for example that avoids waste ofaerosol-generating substrate liquid, preferably while maintaining orimproving aerosol-generating performance of the aerosol-generatingsystem, in which the cartridge is used.

According to a first aspect of the invention there is provided acartridge for use in an aerosol-generating system, for example anelectrically operated aerosol-generating system, comprising a liquidstorage portion for holding a liquid aerosol-forming substrate. Theliquid storage portion comprises at least two parts in fluidcommunication with each other. The first part of the liquid storageportion comprises a heater assembly, a first capillary material,provided in contact with the heater assembly, and a second capillarymaterial in contact with the first capillary material and spaced apartfrom the heater assembly by the first capillary material. The secondpart of the liquid storage portion comprises a container for holdingaerosol-forming substrate in liquid form and preferably arranged forsupplying the liquid to the second capillary material. The second partof the liquid storage portion may comprise a tank that is substantiallyempty and is suitable for holding aerosol-forming substrate in liquidform.

The capillary material is preferably designed such that it is capable ofholding sufficient liquid substrate for several puffs. As the capillarymaterial is located in contact with the heater, the heater is providedindependent of the holding angle of the aerosol-generating liquid withsufficient aerosol-generating liquid. The remaining inner volume of theliquid storage portion comprises no capillary material but represents anempty tank for storing aerosol-generating liquid. Under normal handlingconditions an aerosol-generating medium, in particular anaerosol-generating smoking device, is transported between puffs and thecapillary material will regularly contact and re-absorb newaerosol-generating liquid.

Because of the reduced amount of the capillary material used, the amountof residual liquid remaining in the capillary material after usage ofthe cartridge is smaller than in conventional cartridges in which thewhole liquid storage portion is filled with capillary material.Moreover, performance tests have shown that the TPM (total particulatematter) yield of aerosol-generating smoking devices equipped withcartridges of the present invention is in many examples at leastcomparable to the performance of aerosol-generating smoking devicesequipped with currently available cartridges.

Preferably the liquid capacity of the capillary material is such that itcan hold enough liquid for 30 to 40 puffs or more. A 3 second puff mayinclude about 1 mg to 4 mg of liquid, for example 3 mg to 4 mg ofliquid. Preferably the capacity of the capillary material is betweenabout 30 mg to about 160 mg, preferably 90 mg to about 160 mg or more,preferably 100 mg to 150 mg, for example 130 mg. Where there are twolayers making up the capillary material, the capacity of the first andsecond layers may be such that about 10 to 20% by weight of the liquidcapacity is in the first layer. For example, where the capacity of thecapillary material is 30 puffs, the capacity of the first layer may beabout 5 puffs, and the capacity of the second layer may be about 25puffs.

Without wishing to be bound by any particular theory, it is thought thatby the capillary material having capacity for several puffs, for example30 or more puffs, the risk of leakage from the device is reduced. It isthought that if the capillary material is too small, then on puffing,liquid may be drawn from the reservoir straight through the capillarymaterial and heater without being vapourised, leading to leakage. Alsoby having a capacity of 90 mg and more, a number of puffs can be takenfrom the device, even when the liquid in the reservoir is not in directcontact with the capillary material.

The heater assembly may be substantially flat and may compriseelectrically conductive filaments, without the need for any winding of aheater wire around a capillary wick.

The electrically conductive filaments may lie in a single plane. Aplanar heater assembly can be easily handled during manufacture andprovides for a robust construction.

The electrically conductive filaments may define interstices between thefilaments and the interstices may have a width of between 10 μm and 100μm. The filaments may give rise to capillary action in the interstices,so that in use, liquid to be vapourised is drawn into the interstices,increasing the contact area between the heater assembly and the liquid.

The electrically conductive filaments may form a mesh of size between160 and 600 Mesh US (+/−10%) (i.e. between 160 and 600 filaments perinch (+/−10%)). The width of the interstices is preferably between 75 μmand 25 μm. The percentage of open area of the mesh, which is the rationof the area of the interstices to the total area of the mesh ispreferably between 25 and 56%. The mesh may be formed using differenttypes of weave or lattice structures. Alternatively, the electricallyconductive filaments consist of an array of filaments arranged parallelto one another.

The electrically conductive filaments may have a diameter of between 10μm and 100 μm, preferably between 8 μm and 50 μm, and more preferablybetween 8 μm and 39 μm. The filaments may have a round cross section ormay have a flattened cross-section. The heater filaments may be formedby etching a sheet material, such as a foil. This may be particularlyadvantageous when the heater assembly comprises an array of parallelfilaments. If the heater assembly comprises a mesh or fabric offilaments, the filaments may be individually formed and knittedtogether.

As described in relation to the first aspect, the heater assembly maycomprise at least one filament made from a first material and at leastone filament made from a second material different from the firstmaterial.

The heater assembly may comprise an electrically insulating substrate onwhich the filaments are supported, the filaments extending across anaperture formed in the substrate. The electrically insulating substratemay comprise any suitable material, and is preferably a material that isable to tolerate high temperatures (in excess of 300 degree Celsius) andrapid temperature changes. An example of a suitable material is apolyimide film, such as Kapton®.

The heater assembly may comprise an electrically conductive contact incontact with a plurality of the filaments. The electrically conductivecontact may be provided between the housing of the liquid storageportion and the electrically insulating substrate. The electricallyconductive contact may be provided between the filaments and theelectrically insulating substrate. An aperture may be formed in theelectrically insulating layer, and the cartridge may comprise twoelectrically conductive contacts positioned on opposite sides on theaperture to one another.

A capillary material is preferably a material that actively conveysliquid from one end of the material to another. The capillary materialis advantageously oriented in the housing to convey liquid to the heaterassembly.

The second capillary material may comprise a fibrous structure whereinthe fibres are generally oriented in the direction of movement in theliquid to the heater. The first capillary material may have lessoriented fibres. For example the first capillary material may have thestructure of a felt.

The capillary material may have a fibrous or spongy structure. Thecapillary material preferably comprises a bundle of capillaries. Forexample, the capillary material may comprise a plurality of fibres orthreads or other fine bore tubes. The fibres or threads may be generallyaligned to convey liquid to the heater. Alternatively, the capillarymaterial may comprise sponge-like or foam-like material. The structureof the capillary material forms a plurality of small bores or tubes,through which the liquid can be transported by capillary action. Thecapillary material may comprise any suitable material or combination ofmaterials. Examples of suitable materials are a sponge or foam material,ceramic- or graphite-based materials in the form of fibres or sinteredpowders, foamed metal or plastics material, a fibrous material, forexample made of spun or extruded fibres, such as cellulose acetate,polyester, or bonded polyolefin, polyethylene, terylene or polypropylenefibres, nylon fibres or ceramic. The capillary material may have anysuitable capillarity and porosity so as to be used with different liquidphysical properties. The liquid has physical properties, including butnot limited to viscosity, surface tension, density, thermalconductivity, boiling point and vapour pressure, which allow the liquidto be transported through the capillary device by capillary action.

The capillary material may be in contact with the heater, for examplewith the electrically conductive filaments. The capillary material mayextend into interstices between the filaments. The heater assembly maydraw liquid aerosol-forming substrate into the interstices by capillaryaction. The capillary material may be in contact with the electricallyconductive filaments over substantially the entire extent of theaperture.

The housing may contain two or more different capillary materials,wherein a first capillary material, in contact with the heater element,has a higher thermal decomposition temperature and a second capillarymaterial, in contact with the first capillary material but not incontact with the heater element has a lower thermal decompositiontemperature. The first capillary material effectively acts as a spacerseparating the heater element from the second capillary material so thatthe second capillary material is not exposed to temperatures above itsthermal decomposition temperature. As used herein, “thermaldecomposition temperature” means the temperature at which a materialbegins to decompose and lose mass by generation of gaseous by products.The second capillary material may advantageously occupy a greater volumethan the first capillary material and may hold more aerosol-formingsubstrate that the first capillary material. The second capillarymaterial may have superior wicking performance to the first capillarymaterial. The second capillary material may be cheaper than the firstcapillary material. The second capillary material may be polypropylene.

The first capillary material can be selected from the group of kevlarfelt, ceramic paper, ceramic felt, carbon felt, cellulose acetate, hempfelt, PET/PBT sheet, cotton pad, porous ceramic disc or porous metaldisc.

Preferred materials include Kevlar felt, ceramic paper, ceramic felt,porous ceramic disc or porous metal disc. The first capillary materialmay comprise glass fibre paper or felt. Preferably the first capillarymaterial includes substantially no organic matter.

Preferably the porosity of the first capillary material is less thanthat of the second capillary material. Preferably the pore size of thefirst capillary material is less than that of the second capillarymaterial. The pore size may be for example measured as being an averagepore size for a region of the capillary material. In this way it can beseen that the aerosol-generating substrate moves more efficiently to theheater. In a broad aspect of the invention, a cartridge is providedwhich includes a heater and a capillary material in contact with theheater for supplying aerosol-generating substrate to the heater, whereinthe porosity or pore size of a region of the capillary material adjacentthe heater is less than the porosity or pore size of a region of thecapillary material remote from the heater. Thus a single material may beused, for example which has a gradient of pore size in one or more ofits dimensions.

The first capillary material may have a fiber size/pore size of between0, 1 to 50 μm, preferably of between 0, 5 to 10 μm and most preferablyof about 4 μm. The first capillary material has a density of below 2g/ml, and preferably of about 0.5 g/ml.

The second capillary material can be a so-called high retention material(HRM) material, selected from the group of polypropylene (PP),polyethylene (PE), polyphenylene sulphide (PPS), polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), rolled non-wovenmaterial or rolled felts. Preferably the second capillary materialcomprises a polymeric material. The material may include a coating, forexample to reduce hydrophobicity.

The second capillary material may have a fiber size/pore size of between1 to 100 μm, preferably of between 15 to 40 μm and most preferably ofabout 25 μm. The second capillary material may have a density of below 1g/ml, and preferably of between 0.1 and 0.3 g/ml.

The first capillary material may separate the heater assembly from thesecond capillary material by a distance of at least 0.8 mm, for exampleat least 1.5 mm, and preferably between 0.8 mm and 2 mm in order toprovide a sufficient temperature drop across the first capillarymaterial.

The first and second capillary material can also be made from the samematerial, and can only be distinguished from each other in that theyexhibit different porosities or different capillarity. For example thefirst capillary material can be compressed such that its pore size orporosity is reduced and its capillarity is increased compared to thesecond capillary material which may be used in an uncompressed or atleast in a less compressed state.

In a preferred embodiment the first and the second material are madefrom a single continuous element of the same base material. Morepreferably the material is treated such that a gradient of pore size orporosity is obtained in a direction towards the heater element or theopening, such that the pore size or porosity decreases, for examplecontinuously decreases, within the capillary material towards the heaterelement.

Preferably at least the first capillary material is compressed uponinsertion into the first part of the housing of the liquid storageportion such that its effective pore size or porosity is reduced. Forexample the single continuous element may have the shape of a truncatedcone, wherein the diameter of the circular base of the truncated cone islarger than the inner diameter of the cylindrical housing of the liquidstorage portion, while the diameter of the truncated apex of the conesubstantially corresponds to the inner diameter of the cylindricalhousing of the liquid storage portion. Upon insertion the capillarymaterial at the base of the cone of capillary material is morecompressed than at the area of the truncated apex. The more compressedmaterial represents the first capillary material and the less compressedmaterial represents the second capillary material. The skilled artisanwill readily appreciate that the resulting gradient of compressiondepends on the relative shape chosen for the capillary element and thehousing of the liquid storage portion.

In a particularly preferred embodiment, the capillary element has aregular cylindrical shape with circular cross-section and a predefineddiameter. The inner surface of the housing comprises a tapered portionat the opening end, such that the capillary material is compressed bythis tapered portion upon insertion of the capillary material into thehousing. Preferably the inner surface of the housing has a conical shapesuch that the inner diameter continuously increases from the open endtowards the closed end of the cartridge.

The first capillary material and the second capillary material maycomprise different regions of the same capillary material element.Compression of the capillary material when laced in the housing may besuch that the pore size or porosity of the capillary material reduced orcontinuously reduces towards the heater assembly.

In a further embodiment the first and the second capillary materialagain are formed from a single continuous piece of the same material.The capillary material may be rectangular web of capillary materialhaving a thickness that amounts to below 50%, preferably to about 25% ofthe inner diameter of the cylindrical housing of the cartridge. Thewidth of the web of capillary material corresponds to the peripheralcircumference of the housing. The web of capillary material can have anydesired length and preferably is about half the length of the housing ofthe cartridge. The web of capillary material is rolled up to form acylindrical shape. By rolling up, the central portion of the web iscompressed to a higher degree than the outer portions of the web suchthat a gradient of pore size or porosity is obtained in radial directionof the rolled-up web of capillary material. In the middle the rolled-upcapillary material an air channel is formed.

A tube shaped fluid permeable heater element is provided in the airchannel such that the heater is in direct contact with the inner surfaceof the rolled-up capillary material. Upon rolling up the capillarymaterial the material portion that is closer to the center axis of thecylinder is more compressed than the material in the radial outwardlocated portion of the capillary material. Thus, again a gradient ofpore size is obtained, wherein the pore size of the capillary materialis continuously decreased within the capillary material in the directionto the heater element. The capillary material is in fluid connectionwith a liquid reservoir, wherein the liquid reservoir is provided in thepart of the housing that is not occupied by the capillary material. Apartition is provided within the housing to ensure that the liquidsubstrate is not in direct communication with the air flow channel.

The web of capillary material may also comprise a plurality of layers ofcapillary material, such that the liquid retention properties of thecapillary material can be designed in any desired way that is mostsuitable for the given aerosol-generating system.

In a particular preferred embodiment the heater element is rolled-uptogether with the capillary material, such that in only onemanufacturing step a combined capillary material with radial gradientand included heating element is obtained.

The liquid storage portion may be positioned on a first side of theelectrically conductive filaments and an airflow channel positioned onan opposite side of the electrically conductive filaments to the liquidstorage portion, such that air flow past the electrically conductivefilaments entrains vapourised liquid aerosol-forming substrate.

Preferably, the aerosol generating system comprises a housing.Preferably, the housing is elongate. The housing may comprise anysuitable material or combination of materials. Examples of suitablematerials include metals, alloys, plastics or composite materialscontaining one or more of those materials, or thermoplastics that aresuitable for food or pharmaceutical applications, for examplepolypropylene, polyetheretherketone (PEEK) and polyethylene. Preferably,the material is light and non-brittle. The material may include PET, PBTor PPS.

Preferably, the aerosol-generating system is portable. Theaerosol-generating system may have a size comparable to a conventionalcigar or cigarette. The smoking system may have a total length betweenapproximately 30 mm and approximately 150 mm. The smoking system mayhave an external diameter between approximately 5 mm and approximately30 mm.

The aerosol-forming substrate is a substrate capable of releasingvolatile compounds that can form an aerosol. The volatile compounds maybe released by heating the aerosol-forming substrate.

The aerosol-forming substrate may comprise plant-based material. Theaerosol-forming substrate may comprise tobacco. The aerosol-formingsubstrate may comprise a tobacco-containing material containing volatiletobacco flavour compounds, which are released from the aerosol-formingsubstrate upon heating. The aerosol-forming substrate may alternativelycomprise a non-tobacco-containing material. The aerosol-formingsubstrate may comprise homogenised plant-based material. Theaerosol-forming substrate may comprise homogenised tobacco material. Theaerosol-forming substrate may comprise at least one aerosol-former. Theaerosol-forming substrate may comprise other additives and ingredients,such as flavourants.

Preferably the liquid storage portion comprises an opening and theheater assembly extends across the opening of the housing. The heaterassembly may comprise an electrically insulating substrate on which theheater element is supported. The electrically insulating substrate maycomprise any suitable material, and is preferably a material that isable to tolerate high temperatures (in excess of 300 degree Celsius) andrapid temperature changes. An example of a suitable material is apolyimide film, such as Kapton®. The electrically insulating substratemay have an aperture formed in it, with the heater element extendingacross the aperture. The heater assembly may comprise electricalcontacts connected to the electrically conductive filaments.

According to a second aspect of the invention there is provided acartridge for use in an aerosol-generating system, for example anelectrically operated aerosol-generating system, with a liquid storageportion comprising a housing for holding a liquid aerosol-formingsubstrate, wherein the liquid storage portion comprises at least twoparts in fluid communication to each other. The first part of the liquidstorage portion comprises a first capillary material, provided at thevicinity of the opening of the housing, and a second capillary materialin contact with the first capillary material and spaced apart from theopening by the first capillary material. The second part of the liquidstorage portion may be substantially empty and being suitable forholding aerosol-forming substrate in liquid form.

The cartridge preferably further comprises a fluid permeable heaterassembly extending across the opening of the housing.

In the embodiments of the present invention wherein the first part ofthe liquid storage portion occupies below 50%, preferably between 10%and 30%, more preferably between 15% and 25% and most preferably about20% of the volume of the liquid storage portion.

The capillary material extends across the complete cross-section of thefirst part of the liquid storage portion, such that it is not possiblefor the liquid aerosol-generating substrate to flow directly to theheater assembly or the opening of the cartridge.

According to a further aspect of the invention there is provided anaerosol-generating system comprising a cartridge according to thepresent invention.

The system may further comprise electric circuitry connected to theheater assembly and to an electrical power source, the electriccircuitry configured to monitor the electrical resistance of the heaterassembly or of one or more filaments of the heater assembly, and tocontrol the supply of power to the heater assembly dependent on theelectrical resistance of the heater assembly or the one or morefilaments.

The electric circuitry may comprise a microprocessor, which may be aprogrammable microprocessor. The electric circuitry may comprise furtherelectronic components. The electric circuitry may be configured toregulate a supply of power to the heater assembly. Power may be suppliedto the heater assembly continuously following activation of the systemor may be supplied intermittently, such as on a puff-by-puff basis. Thepower may be supplied to the heater assembly in the form of pulses ofelectrical current.

The system advantageously comprises a power supply, typically a battery,within the main body of the housing. As an alternative, the power supplymay be another form of charge storage device such as a capacitor. Thepower supply may require recharging and may have a capacity that allowsfor the storage of enough energy for one or more smoking experiences;for example, the power supply may have sufficient capacity to allow forthe continuous generation of aerosol for a period of around six minutes,corresponding to the typical time taken to smoke a conventionalcigarette, or for a period that is a multiple of six minutes. In anotherexample, the power supply may have sufficient capacity to allow for apredetermined number of puffs or discrete activations of the heaterassembly.

Preferably, the aerosol generating system comprises a housing.Preferably, the housing is elongate. The housing may comprise anysuitable material or combination of materials. Examples of suitablematerials include metals, alloys, plastics or composite materialscontaining one or more of those materials, or thermoplastics that aresuitable for food or pharmaceutical applications, for examplepolypropylene, polyetheretherketone (PEEK) and polyethylene. Preferably,the material is light and non-brittle.

Preferably, the aerosol-generating system is portable. Theaerosol-generating system may have a size comparable to a conventionalcigar or cigarette. The smoking system may have a total length betweenapproximately 30 mm and approximately 150 mm. The smoking system mayhave an external diameter between approximately 5 mm and approximately30 mm.

The aerosol-forming substrate is a substrate capable of releasingvolatile compounds that can form an aerosol. The volatile compounds maybe released by heating the aerosol-forming substrate.

The aerosol-forming substrate may comprise plant-based material. Theaerosol-forming substrate may comprise tobacco. The aerosol-formingsubstrate may comprise a tobacco-containing material containing volatiletobacco flavour compounds, which are released from the aerosol-formingsubstrate upon heating. The aerosol-forming substrate may alternativelycomprise a non-tobacco-containing material. The aerosol-formingsubstrate may comprise homogenised plant-based material. Theaerosol-forming substrate may comprise homogenised tobacco material. Theaerosol-forming substrate may comprise at least one aerosol-former. Theaerosol-forming substrate may comprise other additives and ingredients,such as flavourants.

Preferably the system comprises a mouthpiece, wherein the cartridge isinserted into the system in an orientation that the opening of thecartridge points away from the mouthpiece.

In another preferred embodiment the cartridge is inserted into thesystem in an orientation that the opening of the cartridge pointstowards the mouthpiece. Depending on the circumstances of usage one ofthese orientations of the cartridge may provide for superior performancecompared to the other.

According to a further aspect of the invention there is provided acartridge for use in an aerosol-generating system, comprising: a liquidstorage portion comprising a housing for holding a liquidaerosol-forming substrate, the liquid storage portion comprising aheater assembly, and a capillary material, provided in contact with theheater assembly, wherein the average porosity or pore size of a regionof the capillary material adjacent the heater assembly is smaller thanthe average porosity or pore size of a region of the capillary materialremote from the heater assembly. A portion of the capillary material inthe region may be compressed to reduce its porosity or pore size. Theliquid storage portion may comprise at least two parts in fluidcommunication with each other, the first part of the liquid storageportion comprising the capillary material, and the second part of theliquid storage portion comprising a container for holdingaerosol-forming substrate in liquid form and supplying the liquid to thehigher porosity or pore size region of the capillary material.

The present invention is also directed to a method for manufacturing acartridge for use in an electrically operated aerosol-generating system,comprising the steps of providing a liquid storage portion comprising ahousing with a first part and a second part, providing heater assembly,placing a first capillary material in the first part of the housing ofthe liquid storage portion, such that first capillary material isprovided in direct contact with the heater assembly, placing a secondcapillary material in the first part of the housing of the liquidstorage portion, such that the second capillary material is in contactwith the first capillary material and is spaced apart from the heaterassembly by the first capillary material. The second part of the liquidstorage portion is substantially empty and is suitable for holdingaerosol-forming substrate in liquid form.

Preferably the first capillary material is compressed during or beforeinsertion into the housing such that its pore size or porosity isreduced compared to the pore size or porosity in the relaxed state.

An aspect of the invention further provides a method of manufacture of acartridge for use in an aerosol-generating system, comprising: providinga liquid storage portion comprising a housing, providing a heaterassembly, placing a capillary material in the housing of the liquidstorage portion, such that the capillary material is provided in directcontact with the heater assembly, wherein the method includes the stepof compressing a portion of the capillary material during or beforeplacing in the housing such that the porosity or pore size of theportion of the capillary material is reduced.

The invention also provides an aerosol-generating system as describedherein being an electrically operated smoking system.

The term “substantially flat” filament arrangement preferably refers toa filament arrangement that is in the form of a substantially twodimensional topological manifold. Thus, the substantially flat filamentarrangement extends in two dimensions along a surface substantially morethan in a third dimension. In particular, the dimensions of thesubstantially flat filament arrangement in the two dimensions within thesurface is at least 5 times larger than in the third dimension, normalto the surface. An example of a substantially flat filament arrangementis a structure between two substantially parallel surfaces, wherein thedistance between these two surfaces is substantially smaller than theextension within the surfaces. In some embodiments, the substantiallyflat filament arrangement is planar. In other embodiments, thesubstantially flat filament arrangement is curved along one or moredimensions, for example forming a dome shape or bridge shape.

The term “filament” preferably refers to an electrical path arrangedbetween two electrical contacts. A filament may arbitrarily branch offand diverge into several paths or filaments, respectively, or mayconverge from several electrical paths into one path. A filament mayhave a round, square, flat or any other form of cross-section. Afilament may be arranged in a straight or curved manner.

The term “filament arrangement” preferably refers to an arrangement ofone or preferably a plurality of filaments. The filament arrangement maybe an array of filaments, for example arranged parallel to each other.Preferably, the filaments may form a mesh. The mesh may be woven ornon-woven.

It will be understood that, where appropriate, features of one aspect ofthe invention may be provided in relation to another aspect of theinvention, in any appropriate combination.

The invention will be further described, by way of example only, withreference to the accompanying drawings in which:

FIGS. 1a to 1d are schematic illustrations of a system, incorporating acartridge, in accordance with an embodiment of the invention FIG. 2shows a cartridge with porous medium according to a first aspect of thepresent invention;

FIG. 3 shows an exploded view of a similar cartridge as shown in FIG. 2;

FIG. 4 shows a cartridge with a single porous medium compressed by theshape of porous material upon insertion into the housing;

FIG. 5 shows a cartridge with a single porous medium compressed by theshape of inner surface of the housing upon insertion into the housing;

FIG. 6 shows a capillary material rolled-up into a cylindrical shape andbeing provided with a tube-shaped heater in the centre.

FIGS. 1a to 1d are schematic illustrations of an aerosol-generatingsystem, including a cartridge in accordance with an embodiment of theinvention. FIG. 1a is a schematic view of an aerosol-generating device10 and a separate cartridge 20, which together form theaerosol-generating system. In this example, the aerosol-generatingsystem is an electrically operated smoking system.

The cartridge 20 contains an aerosol-forming substrate and is configuredto be received in a cavity 18 within the device. Cartridge 20 should bereplaceable by a user when the aerosol-forming substrate provided in thecartridge is depleted. FIG. 1a shows the cartridge 20 just prior toinsertion into the device, with the arrow 1 in FIG. 1a indicating thedirection of insertion of the cartridge.

The aerosol-generating device 10 is portable and has a size comparableto a conventional cigar or cigarette. The device 10 comprises a mainbody 11 and a mouthpiece portion 12. The main body 11 contains a battery14, such as a lithium iron phosphate battery, control electronics 16 anda cavity 18. The mouthpiece portion 12 is connected to the main body 11by a hinged connection 21 and can move between an open position as shownin FIG. 1a to 1c and a closed position as shown in FIG. 1d . Themouthpiece portion 12 is placed in the open position to allow forinsertion and removal of cartridges 20 and is placed in the closedposition when the system is to be used to generate aerosol, as will bedescribed. The mouthpiece portion comprises a plurality of air inlets 13and an outlet 15. In use, a user sucks or puffs on the outlet to drawair from the air inlets 13, through the mouthpiece portion to the outlet15, and thereafter into the mouth or lungs of the user. Internal baffles17 are provided to force the air flowing through the mouthpiece portion12 past the cartridge, as will be described.

The cavity 18 has a circular cross-section and is sized to receive ahousing 24 of the cartridge 20. Electrical connectors 19 are provided atthe sides of the cavity 18 to provide an electrical connection betweenthe control electronics 16 and battery 14 and corresponding electricalcontacts on the cartridge 20.

FIG. 1b shows the system of FIG. 1a with the cartridge inserted into thecavity 118, and the cover 26 being removed. In this position, theelectrical connectors rest against the electrical contacts on thecartridge, as will be described.

FIG. 1c shows the system of FIG. 1b with the cover 26 fully removed andthe mouthpiece portion 12 being moved to a closed position.

FIG. 1d shows the system of FIG. 1c with the mouthpiece portion 12 inthe closed position. The mouthpiece portion 12 is retained in the closedposition by a clasp mechanism, The mouthpiece portion 12 in a closedposition retains the cartridge in electrical contact with the electricalconnectors 19 so that a good electrical connection is maintained in use,whatever the orientation of the system is. The mouthpiece portion 12 mayinclude an annular elastomeric element that engages a surface of thecartridge and is compressed between a rigid mouthpiece housing elementand the cartridge when the mouthpiece portion 12 is in the closedposition. This ensures that a good electrical connection is maintaineddespite manufacturing tolerances.

Of course other mechanisms for maintaining a good electrical connectionbetween the cartridge and the device may, alternatively or in addition,be employed. For example, the housing 24 of the cartridge 20 may beprovided with a thread or groove (not illustrated) that engages acorresponding groove or thread (not illustrated) formed in the wall ofthe cavity 18. A threaded engagement between the cartridge and devicecan be used to ensure the correct rotational alignment as well asretaining the cartridge in the cavity and ensuring a good electricalconnection. The threaded connection may extend for only half a turn orless of the cartridge, or may extend for several turns. Alternatively,or in addition, the electrical connectors 19 may be biased into contactwith the contacts on the cartridge.

Other cartridge designs incorporating a capillary material arrangementin accordance with this disclosure can now be conceived by one ofordinary skill in the art. For example, the cartridge may include amouthpiece portion, may include more than one heater assembly and mayhave any desired shape. Furthermore, a capillary assembly in accordancewith the disclosure may be used in systems of other types to thosealready described, such as humidifiers, air fresheners, and otheraerosol-generating systems

The exemplary embodiments described above illustrate but are notlimiting. In view of the above discussed exemplary embodiments, otherembodiments consistent with the above exemplary embodiments will now beapparent to one of ordinary skill in the art.

The cartridge shown in FIG. 2 comprises a housing 24 made frompolypropylene, with a two-part liquid storage portion. The first part 32of the liquid storage portion comprises a first capillary material 36and a second capillary material 38. The second part 34 of the liquidstorage portion is an empty tank that can be filled or partly filledwith liquid aerosol-generating substrate.

At the upper end of the cartridge a ceramic substrate 42 is provided.The substrate 24 defines an opening 44 and has electric contacts (notshown) at opposite sides thereof. A heater element 46 is connected tothe electrical contacts of the substrate 32 and extends over the opening44 defined by the substrate.

Both the first capillary material 36 and the second capillary material38 retain liquid aerosol-forming substrate. The first capillary material16, which is in direct contact with the heater element 46, has a higherthermal decomposition temperature (at least 160 degree Celsius or highersuch as approximately 250 degree Celsius) than the second capillarymaterial 38. The first capillary material 36 effectively acts as aspacer separating the heater element 46 from the second capillarymaterial 38 so that the second capillary material 38 is not exposed totemperatures above its thermal decomposition temperature. The thermalgradient across the first capillary material 36 is such that the secondcapillary material 38 is exposed to temperatures below its thermaldecomposition temperature. The second capillary material 38 may bechosen to have superior wicking performance to the first capillarymaterial 36, may retain more liquid per unit volume than the firstcapillary material 36 and may be less expensive than the first capillarymaterial 36. In this example the first capillary material 36 is a heatresistant material, such as a fiberglass or fiberglass containingmaterial and the second capillary material 38 is a polymer such as highdensity polyethylene (HDPE), or polyethylene terephthalate (PET).

FIG. 3 is an exploded view of a cartridge similar to the cartridge ofFIG. 2. The cartridge comprises a generally circular cylindrical housing24 comprising a first part 32 and a second part 34. The first part ofthe housing 24 contains a first and a second capillary material 36, 38that are soaked in a liquid aerosol-forming substrate. In this examplethe aerosol-forming substrate comprises 39% by weight glycerine, 39% byweight propylene glycol, 20% by weight water and flavourings, and 2% byweight nicotine. A capillary material here is a material that activelyconveys liquid from one end to another, and may be made from anysuitable material. In this example the capillary material is formed frompolyester.

The housing 24 has an open end to which a heater assembly is fixed. Theheater assembly comprises a substrate 42 having an aperture 44 formed init, a pair of electrical contacts 48 fixed to the substrate 42 andseparated from each other by a gap 40, and an resistive heater element46 extending over the aperture 44 and being fixed to the electricalcontacts 48 on opposing sides of the aperture 44.

The heater assembly is covered by a removable cover 26. The cover 26comprises a liquid impermeable plastic sheet that is glued to the heaterassembly but which can be easily peeled off. A tab is provided on theside of the cover to allow a user to grasp the cover when peeling itoff. It will now be apparent to one of ordinary skill in the art thatalthough gluing is described as the method to a secure the impermeableplastic sheet to the heater assembly, other methods familiar to those inthe art may also be used including heat sealing or ultrasonic welding,so long as the cover may easily be removed by a consumer.

FIG. 4 shows an embodiment wherein the housing 24 has the shape of aregular cylinder with circular cross-section. The first and the secondcapillary material are made from the same material and are integrallyformed as single continuous piece of capillary material 60 having theshape of a truncated cone. The diameter of the truncated apex of thecone corresponds to the inner diameter of the cylindrical housing. Thediameter of the base of the cone is twice as large as the inner diameterof the cylindrical housing. The capillary material 60 is inserted apexfirst into the cylindrical housing 24 until the surface of the base ofthe cone lies flush with the front face of the cylindrical housing. Uponinsertion the capillary material 40 is compressed, whereby due to therelative shape of the capillary material and the cylindrical housing,compression of the capillary material 60 is increased towards end faceof the cylindrical housing. At the same time pore size or porosity ofthe capillary material is reduced such that the pore size or porosity ofthe capillary material in the vicinity of the end face of the housing issmaller than the pore size or porosity of the capillary material locatedin the center of the cylindrical housing. The open end of thecylindrical housing at the right hand side in FIG. 4 is provided with aclosure, such that the inside of the cylindrical housing forms a tankreservoir for holding liquid aerosol-generating substrate. At the otherend the heater assembly as illustrated in FIGS. 2 and 3 can be provided.

FIG. 5 shows an alternative embodiment having a similar effect as theembodiment depicted in FIG. 4. In this case the inner surface of thehousing is provided with a conical shape, such that the interior taperstowards one end of the housing 24. Here the inner diameter of housing 24at the left hand side in FIG. 5 is half the inner diameter of housing 24at the right hand side. Again the first and the second capillarymaterial are made from the same material and are integrally formed assingle continuous piece of capillary material 60. The piece of capillarymaterial 60 has regular cylindrical form with a circular cross-section.The diameter cylindrical piece of capillary material 60 corresponds tothe inner diameter of the housing 24 at the right hand side In FIG. 5.The capillary material 60 is inserted into the housing 24 until an endface of the capillary material 60 lies flush with the smaller diameterfront face of the cylindrical housing, i.e with the end face at the lefthand side of the housing 24. Again the capillary material 60 iscompressed upon insertion, whereby due to the relative shape of thecapillary material and the cylindrical housing, compression of thecapillary material 60 is increased towards the left hand side end faceof the cylindrical housing 24. At the same time pore size or porosity ofthe capillary is reduced such that the pore size or porosity of thecapillary material 60 in the vicinity of the end face of the housing issmaller than the pore size or porosity of the capillary material 60located in the center of the cylindrical housing. Again, the open end ofthe cylindrical housing at the right hand side in FIG. 5 is providedwith a closure, such that the inside of the cylindrical housing forms atank reservoir for holding liquid aerosol-generating substrate. At theother end face of the housing, the heater assembly as illustrated inFIGS. 2 and 3 can be provided.

In FIG. 6a further embodiment is depicted, whereby only the capillarymaterial 50 that is to be used with a cylindrically housing is shown.The first and the second capillary material again are formed from asingle continuous piece of the same material 50. The capillary materialis a rectangular piece web of capillary material having a thickness thatamounts to about 25% of the inner diameter of the cylindrical housing ofthe cartridge. The width of the web of capillary material corresponds tothe peripheral circumference of the housing. The length of the web ofcapillary material is about half the length of the housing of thecartridge. The web of capillary material is rolled up to form acylindrical shape. In the middle of the rolled-up capillary material anair channel 52 is formed. A tube shaped fluid permeable heater element54 is provided in the air channel 52 such that the heater 54 is indirect contact with the inner surface 56 of the rolled-up capillarymaterial 50. Upon rolling up the capillary material the material portion50 a that is closer to the center axis of the cylinder is morecompressed than the material 50 b in the radial outward located portionof the capillary material. Thus, again a gradient of pore size orporosity is obtained, wherein the pore size or porosity of the capillarymaterial 50 is continuously decreased within the capillary material inthe direction towards the heater element 54. The capillary material isin fluid connection with a liquid reservoir (not shown), wherein theliquid reservoir is provided in the part of the housing that is notoccupied by the capillary material. A partition is provided within thehousing to ensure that the liquid substrate is not in directcommunication with the air flow channel 52.

It will be understood that different methods and configurations arepossible to obtain the capillary material having a different pore sizeor porosity in different regions. In each example, a region of smallerpore size or porosity is located at one end of the capillary material.The region of smaller pore size or porosity is then located at theheater. The gradient in pore size or porosity then enhances thecapillary action in the material, to draw aerosol-generating substrateliquid to the heater.

1. A cartridge for an aerosol-generating system, comprising: a liquidstorage portion comprising: a housing including an air flow channeltherein, a liquid reservoir configured to hold a liquid aerosol-formingsubstrate, a partition disposed between the air flow channel and theliquid reservoir, a heater assembly disposed in the air flow channel, afirst capillary material disposed in contact with the heater assembly,and a second capillary material disposed in contact with the firstcapillary material and the liquid reservoir, and being spaced apart fromthe heater assembly by the first capillary material, wherein an averagepore size of the first capillary material or an average porosity of thefirst capillary material is less than an average pore size of the secondcapillary material or an average porosity of the second capillarymaterial.
 2. The cartridge according to claim 1, wherein the firstcapillary material and the second capillary material comprise differentregions of a same piece of capillary material.
 3. The cartridgeaccording to claim 2, wherein the same piece of the capillary materialis a rectangular webbed piece of capillary material.
 4. The cartridgeaccording to claim 3, wherein the rectangular webbed piece of thecapillary material has a thickness that is about 25% of an innerdiameter of the housing.
 5. The cartridge according to claim 3, whereina length of the rectangular webbed piece of the capillary material isabout half of a length of the housing.
 6. The cartridge according toclaim 3, wherein the rectangular webbed piece of the capillary materialis rolled in a cylindrical shape.
 7. The cartridge according to claim 2,wherein a portion of the same piece of the capillary material that isdisposed closer to the heater assembly is under greater compression thananother portion of the same piece of the capillary material that isdisposed farther from the heater assembly in a radially outwarddirection.
 8. The cartridge according to claim 2, wherein the averagepore size of the same piece of the capillary material or the averageporosity of the same piece of the capillary material continuouslyincreases with increasing distance from the heater assembly in aradially outward direction.
 9. The cartridge according to claim 1,wherein the heater assembly is a tube-shaped fluid-permeable heaterelement.
 10. The cartridge according to claim 1, wherein the housing iscylindrical and extends in a longitudinal direction of the liquidstorage portion.
 11. The cartridge according to claim 1, wherein theliquid reservoir is disposed in a part of the housing that is notoccupied by the first capillary material and the second capillarymaterial.
 12. The cartridge according to claim 1, wherein the firstcapillary material has an average fiber size or an average pore size ofbetween 0.1 μm to 50 μm.
 13. The cartridge according to claim 1, whereinthe first capillary material has an average density of below 2 g/ml. 14.The cartridge according to claim 1, wherein the second capillarymaterial has an average fiber size or an average pore size of between 1μm to 100 μm.
 15. The cartridge according to claim 1, wherein the secondcapillary material has an average density of below 1 g/ml.
 16. Thecartridge according to claim 9, wherein the tube-shaped fluid-permeableheater element is disposed in direct contact with a radially innermostsurface of the first capillary material.
 17. The cartridge according toclaim 2, wherein the same piece of the capillary material iscylindrically shaped such that an average pore size of the same piece ofthe capillary material or an average porosity of the same piece of thecapillary material increases as a function of distance in a radiallyoutward direction from the heater assembly.
 18. The cartridge accordingto claim 6, wherein the air flow channel extends in a longitudinaldirection of the housing through a central longitudinal axis of thecylindrical shape of the rectangular webbed piece of the capillarymaterial.
 19. A method of manufacturing a cartridge for anaerosol-generating system, comprising: providing a liquid storageportion comprising a housing including an air flow channel therein;providing a liquid reservoir configured to hold a liquid aerosol-formingsubstrate; placing a partition between the air flow channel and theliquid reservoir; placing a heater assembly in the air flow channel;placing a first capillary material in contact with the heater assembly;and placing a second capillary material in contact with the firstcapillary material and the liquid reservoir, and being spaced apart fromthe heater assembly by the first capillary material, wherein an averagepore size of the first capillary material or an average porosity of thefirst capillary material is less than an average pore size of the secondcapillary material or an average porosity of the second capillarymaterial.
 20. An aerosol-generating system, comprising: a cartridgecomprising a liquid storage portion, the liquid storage portioncomprising: a housing including an air flow channel therein, a liquidreservoir configured to hold a liquid aerosol-forming substrate, apartition disposed between the air flow channel and the liquidreservoir, a heater assembly disposed in the air flow channel, a firstcapillary material disposed in contact with the heater assembly, and asecond capillary material disposed in contact with the first capillarymaterial and the liquid reservoir, and being spaced apart from theheater assembly by the first capillary material, wherein an average poresize of the first capillary material or an average porosity of the firstcapillary material is less than an average pore size of the secondcapillary material or an average porosity of the second capillarymaterial.